Export bezier curves
Now I have found a way to export the bezier curves in world coordinates. To do so I name all my bezier curves "BezierCurve01", "BezierCurve02",...,"BezierCurve18" and so on. I also have to make sure that the curves are in exactly this order in the table bpy.data.curves. This is achieved by simply renaming every curve. Then I can run the following script to get the desired output:

import bpy
import os

currPath = os.path.splitext(bpy.data.filepath)[0]+".txt"
file = open(currPath, "w") 
i = 1

for curves in bpy.data.curves:
    idx = str(i)
    if i &lt; 10:
      bezier = "BezierCurve0"+idx
    else:
      bezier = "BezierCurve"+idx
    ob = bpy.data.objects.get(bezier, None)
    for splines in curves.splines:
        for x in range(len(splines.bezier_points)): 
            file.write("p ")
            handle_left = ob.matrix_world * splines.bezier_points[x].handle_left
            handle_left *= 11
            co = ob.matrix_world * splines.bezier_points[x].co
            co *= 11
            handle_right = ob.matrix_world * splines.bezier_points[x].handle_right
            handle_right *= 11
            file.write("%.3f " % (handle_left.y))
            file.write("%.3f " % (-handle_left.x))
            file.write("%.3f " % (handle_left.z)) 
            file.write("%.3f " % (co.y)) 
            file.write("%.3f " % (-co.x)) 
            file.write("%.3f " % (co.z))
            file.write("%.3f " % (handle_right.y))
            file.write("%.3f " % (-handle_right.x)) 
            file.write("%.3f " % (handle_right.z))
            file.write("\n")
    file.write("n\n")
    i = i + 1

file.close()


This only works for 20 curves and has to be adjusted properly for more.